1. Field of the Invention
This invention relates to plastic wads used in cartridges for shotguns. In particular, the invention relates to a one-piece wad structure having an obturating disc or cup which is connected to a shot cup by a filler comprising a shock absorbing structure having improved folding or structural deflection characteristics.
2. Description of the Prior Art
It is known to provide plastic wad structures for use in shotgun shells to (1) house the shot charge, (2) obturate combustion gases, and (3) cushion the shot charge when the loaded wad is fired from the gun. It is necessary to cushion the shot charge from the impact generated by the expanding power gases upon firing. This is necessary so that the shot will be gradually set in motion. This prevents undue deformation of the shot as well as lessening maximum pressure levels required in the shell to achieve a given shot load velocity.
It is also necessary that the filler or cushioning portion of the wad structure provide a cushioning action that is uniform in order to prevent any tilting or yawing of the shot cluster.
Attempts have been made in the prior art to provide wads with improved filler or cushioning structures. These attempts however have not been successful and are characterized by devices that are less than ideal since they exhibit a nonuniform, asymmetrical and uncontrolled deformation of the cushion members. This, in turn, prevents the attainment of a controllable and predictable shot pattern.